I got a Super Saturday invite earlier today as well. Am researching tickets and they are relatively cheap for that weekend. Looking again tomorrow morning before I make my decision. (I hear Tuesdays mornings are the best time to buy domestic plane tickets. Is this an urban myth?)
Looking forward to it.
ETA - I've decided to go ahead and book tickets to Super Saturday. I have a friend at Michigan Law that I can stay with, and, while I believe that all interview sites are equivalent in their eyes, I did meet a recruiter at an MBA fair in New York in September that told me that the adcom takes a campus visit very seriously. I think they like knowing that you think Ann Arbor is a cool town. I've never been, so I figured I'd kill two birds with one stone.